560 proceedings: botanical society 



and Florida, and its cultivation seems likely to become important in 

 those States. In order that this new industry may be built upon solid 

 foundations the Department of Agriculture, through the Office of 

 Foreign Seed and Plant Introduction, has undertaken to conduct an 

 exploration of those parts of tropical America where avocados are 

 grown, for the purpose of obtaining the best available varieties as well 

 as information regarding the requirements of the tree. The work in 

 Guatemala, which extended over sixteen months in 1916 and 19 17, 

 resulted in the introduction of about 25 new and promising sorts. 



The avocado is the principal fruit tree of the Guatemalan highlands, 

 and ranks alongside the banana as a source of human food. The 

 Guatemalan Indians use it largely in the place of meat. The tree is 

 found in Guatemala at all elevations between sea-level and 8500 feet, 

 at which latter altitude severe frosts occur. It is significant that 

 avocados are grown in regions which are considered too cold for the 

 orange, the latter fruit not being found above 7500 feet. 



In addition to avocados, numerous other plants were obtained and 

 introduced into the United States. These include several varieties of 

 the chayote, a promising new vegetable for the South; the large-fruited 

 Guatemalan haw, Crataegus stipiilosa; the Central American cherry, 

 Prunns salicifolia; choice varieties of the cherimoya for cultivation in 

 California; a beautiful dwarf Chamaedorea which gives promise of 

 being valuable as a house plant; two new dahlias, one a double-flowered 

 tree dahlia which has been named D. maxonii, and the other a smaller 

 plant, considered by W. E. Safford, who has named it D. popenovii 

 to be one of the ancestors of the cultivated race of cactus dahlias; the 

 beautiful blue-flowered Guatemalan lignum-vitae, Guaiacum gtiate- 

 malense, which promises to do well in Florida; a new blue-flowered 

 Salvia; and the little-known ilama, Annona diver sifolia, a fruit which 

 resembles the cherimoya and deserves to be cultivated in all tropical 

 countries. 



Carbon monoxide, a respiration product of Nereocystis luetkeana: 

 Seth C. Langdon and W. R. GailEy (by invitation). The data con- 

 tained in this paper were obtained at Puget Sound Marine Station in an 

 investigation to determine if the carbon monoxide present in the pneu- 

 matocysts of the giant Pacific Coast kelp was an intermediate step in 

 photosynthesis or a respiratory product. It was found that carbon 

 monoxide was formed only when oxygen was present in the gas. The 

 carbon monoxide was produced just as readily in the dark as in the 

 light, hence its formation is related to respiration rather than to anabolic 

 processes. 



special meeting 



The Botanical Society of Washington met at the Cosmos Club at 

 8 p.m., July I, 1919, in special session in honor of Dr. A. D.Cotton, 

 Royal Botanical Garden, Kew, England, Pathologist to the Board of 

 Agriculture and Fisheries of England and Wales; Dr. Geo. H. Pethy- 

 BRiDGE, Economic Botanist to the Department of Agriculture and Tech- 



